There is a developing need for a building panel that can be used in various structures such as schools, offices, commercial and industrial buildings, ships, etc. and which will have excellent fire resistance. It would be desirable to provide a highly fire resistant building panel that can be made in various forms suitable for use as an interior or exterior building panel, an insulating or non-insulating panel, or a building panel having high strength and capable of holding mechanical fasteners such as rivets, bolts, etc. A lightweight building panel has maximum utility for most such uses so as not to impose undue additional loading on the structure to which it is attached.
For example, many buildings have been constructed in recent years that have a large number of windows. This has been especially true for large structures such as office buildings, factories, commercial buildings and schools and other municipal buildings. The buildings often utilize a curtain wall type of exterior wall which incorporates a high percentage of window area. The windows are generally responsible for most of the heat loss from a building. The ever-increasing energy costs and contemporary awareness of the need for energy conservation have created a demand for retrofit building panels having high insulating properties that can be applied over the exterior walls of buildings to reduce heat loss, and thereby better control the costs of heating or cooling a building. Further, however, there also is an increased concern regarding the fire resistant characteristics of insulating panels, particularly in the case of municipal buildings such as schools. One type of commercially-available building panel that has been sold to meet this need for an exterior insulating panel is constructed of spaced layers of polyester resin reinforced with fiberglass and having plastic foam between the layers. This type of panel has been sold by the assignee of this application and other companies in the field. While suitable for some installations, panels made with polyester resins have not been able to meet more stringent fire resistant characteristics presently demanded by many building owners and regulatory authorities.
In the case of ships, as another example, it is often desired to incorporate interior building panels in bulkhead partitioning and the like. The panels should have high fire resistance for safety reasons, particularly in the case of naval ships. It is generally required for this type of use, in addition, that the panels exhibit excellent mechanical strength and be able to retain fasteners so that various objects can be secured to the panels.
Also, interior building panels that can be used to cover interior walls or partition open areas into working spaces, for example, desirably should have excellent fire resistance to maximize the safety of the building occupants. In many cases, interior building panels need have low or little insulating properties, although it is also sometimes desirable that they be constructed to provide insulation to reduce thermal losses. It is usually preferable that interior building panels be light in weight in order to minimize the load imposed on the structural elements of a building.
Accordingly, one of the principal objects of this invention was to develop a structural building panel capable of a high degree of fire resistance, yet light enough in weight so as not to overload the existing building structure. A further main object was to develop a fire resistant building panel that can be made as a panel with either high or low insulating characteristics, depending upon the intended end use. Yet another principal object was to provide a fire resistant building panel construction using synthetic plastic materials that can be adapted for use as either an exterior panel or an interior panel. Another was to provide a fire resistant building panel of reinforced plastic material that is capable of holding mechanical fasteners. Another was to develop a fire resistant structural building panel having at least one surface which can be provided with an attractive surface texture or can be painted. Another main object was to develop appropriate methods for the manufacture of building panels of the foregoing types.